Comparing PHP to CGI/Perl is pointless. Compare PHP to either Apache::EmbPerl or HTML::Mason, and you are starting to get a fair comparison.

Having watched PHP develop over the years, it started out as a very simple Perl replacement, but then has been slowly adding features of Perl one by one, but three to five years later. In another five years, it'll probably be where Perl is now.

So why wait? With Perl, you get a mature language, and a language that works as well off the web as on. And HTML::Mason and everything else in the CPAN make leveraging other people's implementation a snap for nearly any common task.